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Methods and apparatus for producing composite-coated rigid flat-rolled sheet metal substrate in which thermoplastic polymeric materials are selected and combined for dual-layer molten-film extrusion presenting a first-contacting tie-layer and an externally-located finish-layer which are simultaneous

Methods and apparatus for producing composite-coated rigid flat-rolled sheet metal substrate in which thermoplastic polymeric materials are selected and combined for dual-layer molten-film extrusion presenting a first-contacting tie-layer and an externally-located finish-layer which are simultaneously extruded for a single substrate surface at-a-time; in which tie-layer selection includes an ethylene-glycol modified PET, requiring a substrate-surface temperature between 230° F. and 300° F., and a maleic-anhydride modified polyethylene free of any substrate-surface heating requirement; the tie-layer provides sufficient green-strength-adhesion for a finish-layer selected from PBT, PET, and a combination of PBT and PET; each substrate-surface is separately activated for desired adhesion and separately polymeric coated; dual-surface finishing-processing is carried-out by remelting the coated polymeric materials for completing bonding of the dual polymeric layers on each inorganic-metallic protectively-coated surface of the substrate.

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The invention claimed is: 1. A process for coating a metal sheet, comprising: A) in-line transporting a metal sheet having opposed substantially planar first and second surfaces extending between opposite lateral edges, the first surface having an inorganic-metallic protective coating extending bet

The invention claimed is: 1. A process for coating a metal sheet, comprising: A) in-line transporting a metal sheet having opposed substantially planar first and second surfaces extending between opposite lateral edges, the first surface having an inorganic-metallic protective coating extending between the lateral edges; B) activating a first metallic surface of the inorganic-metallic protective coating to enhance reception and retention of a multi-layer polymeric coating on the activated first metallic surface; C) melt co-extruding the multi-layer polymeric coating on the activated first metallic surface and beyond the opposite lateral edges to establish overhang portions, the multi-layer polymeric coating comprising (i) a polymeric tie layer contacting the activated first metallic surface in direct surface-to-surface contact, the tie layer comprising anhydride-modifled polyethylene, while presenting the activated first surface at ambient temperature; and (ii) a polymeric finish layer in overlaying and coextensive relationship with the tie layer, the finish layer comprising a member selected from polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and a combination of PBT and PET; D) solidifying the extruded multi-layer polymer coating, including the overhang portions; and E) subjecting the extruded multi-layer polymeric coating to finish-treatment, comprising heating the extruded multi-layer polymeric coating at least to a melt temperature thereof, then cooling the multi-layer polymeric coating through a glass-transition temperature thereof at a sufficiently rapid rate to establish amorphous non-directional characteristics in the multi-layer polymeric coating. 2. The process of claim 1, wherein said activating step (B) comprises a member selected from the group consisting of: (i) impinging an open-flame on the first metallic surface for burning-off light oil and surface debris, if any, while controlling chemical content of the flame for producing an oxidizing reaction on the first metallic surface causing loss of surface electrons, (ii) ionizing gas contiguous to the first metallic surface by corona-discharge for activating the first metallic surface; and (iii) a combination of (i) and (ii), in any order. 3. The process of claim 1, wherein said solidifying step (D) comprises removing heat from the polymeric coating by initially contacting the tie layer with the first metallic surface, and contacting the finish-layer with an in-line temperature-modulating surface. 4. The process of claim 1, further comprising: F) directing the metal sheet with the polymeric coating for assembly in a form suitable for transfer. 5. The process of claim 1, further comprising: F) trimming the solidified overhang portions. 6. The process of claim 5, further comprising: G) measuring thickness of the polymeric coating; and H) providing measured thickness as feedback data for controlling said melt co-extruding step (C). 7. The process of claim 1, wherein the metal sheet is selected from the group consisting of low-carbon steel, aluminum, and aluminum/magnesium alloy. 8. The process of claim 7, wherein the inorganic-metallic protective coating is selected from the group consisting of electrolytic-plated tin, electrolytic-plate chrome/chrome oxide, electrolytic-plated zinc, cathodic-dichromate, and hot-dip coated zinc spelter. 9. The process of claim 1, wherein: the metal sheet comprises a member selected from aluminum having at thickness gauge of about 0.005 inch to about 0.25 inch, and aluminum magnesium alloy having a thickness gauge of about 0.0045 inch to about 0.2 inch; and the inorganic-metallic protective coating comprises a member selected from surface oxidation, a chemical conversion coating, an electrochemical conversion coating, chromizing, and a chromate coating. 10. The process of claim 1, wherein: the metal sheet comprises flat-rolled low-carbon steel; the inorganic-metallic protective coating comprises hot-dip zinc spelter having a coating thickness in a range of about 0.0005 inch to about 0.0015 inch; and the finish-layer further comprises an antimicrobial agent selected from particulate copper, and particulate silver encased in zeolite. 11. The method of claim 1, wherein said in-line transporting step (A) moves the metal strip at a rate in a range of about 500 ft/min to about 800 ft/min. 12. A process for coating a metal sheet, comprising: A) in-line transporting a metal sheet having opposed substantially planar first and second surfaces extending between opposite lateral edges, the first and second surfaces having first and second inorganic-metallic protective coatings, respectively, extending between the lateral edges; B) activating a first metallic surface of the first inorganic metallic protective coating to enhance reception and retention of a first multi-layer polymeric coating on the activated first metallic surface; C) melt co-extruding the first multi-layer polymeric coating in direct surface-to-surface contact on the activated first metallic surface and beyond the opposite lateral edges to establish first overhang portions, the first multi-layer polymeric coating comprising (i) a first polymeric tie layer contacting the activated first metallic surface, the first tie layer comprising anhydride-modified polyethylene, while presenting the activated first metallic surface at ambient temperature; (ii) a first polymeric finish layer in overlaying and coextensive relationship with the first tie layer, the first finish layer comprising a member selected from polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and a combination of PBT and PET; D) solidifying the extruded first multi-layer polymer coating, including the first overhang portions; E) activating a second metallic surface of the second inorganic metallic protective coating to enhance reception and retention of a second multi-layer polymeric coating on the activated second metallic surface; F) melt co-extruding the second multi-layer polymeric coating in direct surface-to-surface contact on the activated second metallic surface and beyond the opposite lateral edges to establish second overhang portions, the second multi-layer polymeric coating comprising (i) a second polymeric tie layer contacting the activated second metallic surface, the second tie layer comprising a member selected from (a) ethylene glycol modified PET, while presenting the activated second surface at a temperature in a range of about 230° F. and about 300° F.; and (b) anhydride-modified polyethylene, while presenting the activated second surface at ambient temperature; (ii) a second polymeric finish layer in overlaying and coextensive relationship with the second tie layer, the second finish layer comprising a member selected from (c) a combination of PBT and PET; (d) PBT; and (e) PET; G) solidifying the extruded second multi-layer polymer coating, including the second overhang portions; and H) subjecting the extruded multi-layer polymeric coatings to finish-treatment, comprising heating the extruded multi-layer polymeric coatings at least to a melt temperature thereof, then cooling the multi-layer polymeric coatings though a glass-transition temperature thereof at a sufficiently rapid rate to establish amorphous non-directional characteristics in the multi-layer polymeric coatings. 13. The process of claim 12, wherein said activating steps (B) and (E) comprise a member selected from the group consisting of: (i) impinging an open-flame on the first and second metallic surfaces for burning-off light oil and surface debris, if any, while controlling chemical content of the flame for producing an oxidizing reaction on the first and second metallic surfaces causing loss of surface electrons, (ii) ionizing gas contiguous to the first and second metallic surfaces by corona-discharge for activating the first and second metallic surfaces; and (iii) a combination of (i) and (ii), in any order. 14. The process of claim 12, wherein: said solidifying step (D) comprises removing heat from the first polymeric coating by initially contacting the first tie layer with the first metallic surface, and contacting the first finish-layer with a first in-line temperature-modulating surface; and said solidifying step (G) comprises removing heat from the second polymeric coating by initially contacting the second tie layer with the second surface, and contacting the second finish-layer with a second in-line temperature-modulating surface. 15. The process of claim 12, further comprising: I) directing the metal sheet with the polymeric coatings for assembly in a form suitable for transfer. 16. The process of claim 12, further comprising: I) trimming the first and second solidified overhang portions. 17. The process of claim 16, further comprising: J) measuring thickness of the first and second polymeric coatings; and K) providing measured thickness as feedback data for controlling said melt co-extruding steps (C) and (F). 18. The process of claim 12, wherein the metal sheet is selected from the group consisting of low-carbon steel, aluminum, and aluminum/magnesium alloy. 19. The process of claim 18, wherein the inorganic-metallic protective coatings are selected from the group consisting of electrolytic-plated tin, electrolytic-plate chrome/chrome oxide, electrolytic-plated zinc, cathodic-dichromate, and hot-dip coated zinc spelter. 20. The process of claim 12, wherein: the metal sheet comprises a member selected from aluminum having at thickness gauge of about 0.005 inch to about 0.25 inch, and aluminum magnesium alloy having a thickness gauge of about 0.0045 inch to about 0.2 inch; and the inorganic-metallic protective coatings comprise a member selected from surface oxidation, a chemical conversion coating, an electrochemical conversion coating, chromizing, and a chromate coating. 21. The process of claim 12, wherein: the metal sheet comprises flat-rolled low-carbon steel; the inorganic-metallic protective coatings comprise hot-dip zinc spelter having a coating thickness in a range of about 0.0005 inch to about 0.0015 inch; and the first and second finish-layers further comprise an antimicrobial agent selected from particulate copper, and particulate silver encased in zeolite. 22. The method of claim 12, wherein said in-line transporting step (A) moves the metal strip at a rate in a range of about 500 ft/min to about 800 ft/min. 23. A process of composite coating an elongated flat-rolled sheet metal substrate, comprising: A) supplying an elongated flat-rolled rigid sheet metal substrate by selecting an inorganic-metallic protective coating for each of its pair of substantially-planar opposed surfaces which extend width-wise between longitudinally-extending lateral edges of said substrate, B) controlling substrate movement in the direction of its length; while activating a metallic surface of the inorganic-metallic protective coating on one of the surfaces of the substrate for enhancing adhesion of extruded molten thermoplastic polymeric material, with such surface-activation being selected from the group consisting of (i) impinging an open-flame on said metallic surface for burning-off light oil and surface debris, if any, while controlling chemical content of said flame for producing an oxidizing reaction on said metallic surface causing loss of surface electrons, (ii) ionizing gas contiguous to said metallic surface by corona-discharge for activating said metallic surface, and (iii) combinations of (i) and (ii), in any order; C) presenting said metallic surface for deposition of an extruded molten film of polymeric coating materials, including (i) a molten thermoplastic polymeric material tie-layer for first-contacting said activated metallic surface, comprising anhydride-modified polyethylene, while presenting said activated metallic surface at ambient temperature; and, further including (ii) a molten thermoplastic polymeric material finish-layer, in overlaying and co-extensive relationship with said tie-layer, selected from the group consisting of polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and a combination of PBT and PET; D) preparing said selected polymeric coating materials as separately supplied for each said layer, by (i) heating said polymeric materials to melt temperature, (ii) pressurizing and continuing heating said molten polymeric materials, while (iii) combining said polymeric materials for simultaneous molten film extrusion; E) controlling travel of said substrate in the direction of its length presenting said activated metallic surface; F) extruding said molten-film polymeric materials under pressure on said activated metallic surface presented at ambient temperature, with (i) said tie-layer being inner-located for first-contacting said activated metallic surface in direct surface-to-surface contact, and with (ii) said finish-layer being externally located in overlapping and co-extensive relationship with said tie-layer; G) depositing said molten film polymeric materials simultaneously to extend widthwise between lateral edges of said strip, and to extend further (i) forming a polymeric-overhang of said dual layers extending beyond each lateral edge of said activated metallic surface, followed by (ii) removing heat from said polymeric materials (a) by initial contact of said tie-layer with said metallic surface, (b) by contact of said finish-layer with an in-line temperature-modulating surface, including (c) controlling temperature of said in-line surface, for completing solidification of said polymeric materials; then H) activating the metallic surface of the remaining inorganic metallic protective coating on the opposed substantially-planar surface of said elongated substrate while traveling in the direction of its length, by carrying-out said steps, as set forth in Paragraph B above, for enhancing adhesion of polymeric materials on said remaining activated metallic surface; I) presenting said activated metallic surface for molten-film extrusion of thermoplastic polymeric materials, as set forth in Paragraph C) above; including J) preparing said polymeric materials for extrusion as set forth in Paragraph D) above; K) controlling travel of said substrate in the direction of its length, as set forth in Paragraph E above; L) presenting said remaining activated metallic surface for molten-film extrusion coating by said molten polymeric materials, under pressure, as set forth in Paragraph F) above; M) depositing said combined molten polymeric materials with respect to said remaining activated metallic surface and solidifying said layers as set forth in Paragraph G) above; followed by N) remelting said dual-layer polymeric materials simultaneously on each said metallic surface while said substrate is traveling in the direction of its length; including the steps of (i) selecting a remelt temperature for both said polymeric layers on each metallic surface, (ii) providing for in-line travel of such substrate in the direction of its length substantially at said remelt temperature, prior to initiating cooling, so as to enable completing coverage by said first-contacting tie-layer with said inorganic-metallic topography of the protective coating on each substrate surface; and, also for (iii) augmenting interlinking of polymeric materials of said tie-layer and said external-finish layer, on each said opposed substrate surface; then O) rapidly cooling said dual-layer polymeric materials substantially-simultaneously on both said opposed surfaces through glass transition temperature, resulting in (i) establishing amorphous characteristics in said polymeric coating materials on each said opposed surface, while also (ii) cooling said metal substrate to a temperature to avoid later raising said polymeric materials to a glass transition temperature; and P) directing said elongated substrate, as composite coated on both surfaces, for assembly in a form suitable for transfer. 24. The process of claim 23, further including subsequent to solidification of said polymeric materials as associated with each respective metallic surface, trimming said polymeric overhang as associated with each said metallic surface, and measuring thickness of said dual-layer polymeric materials on each respective metallic surface for maintaining desired uniform coating on each said respective metallic surface. 25. The process of claim 24, comprising; selecting flat-rolled rigid sheet metal substrate from the group consisting of (i) low-carbon steel, (ii) aluminum, and (iii) aluminum/magnesium alloy. 26. The process of claim 25, including (a) selecting rigid flat-rolled low-carbon steel substrate having a thickness gauge in a range about 0.004" to about 0.015", and (b) selecting an inorganic non-ferrous metallic protective coating, for each said opposed substantially-planar surface of said steel substrate, from the group consisting of: electrolytic plated tin electrolytic-plated chrome/chrome oxide electrolytic-plated zinc cathodic-dichromate, and hot-dip coated zinc spelter. 27. The process of claim 25, including (a) selecting rigid flat-rolled substrate, from the group consisting of (i) aluminum having a thickness gauge of about 0.005" to about 0.25"; and (ii) aluminum magnesium alloy having a thickness gauge of about 0.00451" and above 0.2", with (b) an inorganic metallic protective coating for each opposed planar surface selected from the group consisting of (1) surface oxidation, (2) a chemical conversion coating, (3) an electrochemical conversion coating (4) chromizing, and (5) a chromate coating. 28. The process of claim 26, including (a) selecting flat-rolled low-carbon steel substrate having a hot-dip zinc spelter coating, with spelter coating thickness being in the range of about 0.0005" to about 0.0015" total both surfaces, and, further (b) selecting, for inclusion in said thermoplastic-polymeric material finish-layer, for at least one substrate surface, an antimicrobial agent selected from the group consisting of: (i) particulate copper, and (ii) particulate silver encased in zeolite.